In certain fuel systems, such as for vehicles, a pump is provided to move fuel through the system such as from the tank to the engine. A filter element is sometimes provided downstream (on the pressure side) of the pump to protect downstream components. At start-up and during operation of the system, air can be pushed into the filter housing. It is desirable to vent the accumulated air in the housing to avoid the air being pushed through the element. The air can create erratic fuel delivery, and effect performance of the downstream components.
One solution is to provide a vent orifice in the upper part of the housing. Such a orifice allows the air to bleed slowly out of the housing as the housing is filled with fuel. By sizing the orifice appropriately, and locating the orifice in the upper part of the housing, the orifice will essentially only allow air to vent out. Any loss of fuel is fairly insignificant and can be collected and directed with the air back to tank.
It is also known to locate the vent orifice in the top of a centrally located standpipe, and drain the air/fuel through the standpipe. This requires a seal between the upper end cap and standpipe to separate the incoming, dirt fuel from the outgoing, clean and filtered fuel.
While the above solutions have received some acceptance in the market, they generally require additional valves, seals, plumbing and/or relatively complex components in order to function properly. This can increase the cost of the assembly, and can also add size and weight. And since the vent orifice is part of the housing structure, the orifice must be periodically inspected and cleaned in order to ensure it is not clogged by particulate matter.
Thus, it is believed there is a demand for a filter assembly and element for fluid applications which require a purging of air, where the filter assembly has a simple, low cost design, and where the vent orifice is replaced at regular intervals to minimize the chance of clogging.